On Tue, Jul 05, 2011 at 08:40:55PM +0200, Lennart Poettering wrote: > On Tue, 05.07.11 20:36, Lennart Poettering (mzerqung@xxxxxxxxxxx) wrote: > > > > > We'd like to request that virtio-serial devices (/dev/virtio-ports/*) > > > > are tagged so we can use them as systemd devices. Dan Berrange thinks > > > > the right incantation is to add: > > > > > > > > SUBSYSTEM=="virtio-ports", TAG+="systemd" > > > > > > > > to /lib/udev/rules.d/99-systemd.rules > > > > > > The goal is that we want to automagically run /usr/sbin/guestfsd > > > when /dev/virtio-ports/org.libguestfs.channel.0 is present. For > > > this I believe we need to have a '.device' unit for the virtio-port > > > device populated from the above udev rule, so we can in turn have a > > > guestfsd.service unit looking like: > > > > I think adding such a rule to systemd's unit file is not a bad idea, but > > since the use case here is very specific to your app, another option > > would be to add an app-specific udev rule for this. (See below) > > Oops, wanted to write "systemd's udev rules file" here, and not > "systemd's unit file". > > > Either way I have now added to git a patch that marks virtio ports for > > exposure in systemd, by marking them with "systemd". > > So, I am a bit confused now after reading this: > > http://fedoraproject.org/wiki/Features/VirtioSerial > > How does /dev/hvcxxx relate to these virtio ports? > > hvc ports are tagged "systemd" anyway in udev, so if this is the same > thing, why do we have to tag the virtio ports too? > > Can you explain how hvc and virtio relate to each other and under which > kernel device names they show up in udev and how they correspond? In QEMU, there is one PCI device "virtio-serial-pci". In QEMU's view this device is a bus to which we then attach zero or more 'virtconsole' or 'virtserialport' devices. The 'virtconsole' device is a paravirt text console, which appears as /dev/hvcNNN in the guest. These are intended for interactive login and would be expected to run a mingetty/agetty process. You can enable this in a libvirt guest by changing the default <console type='pty'/> To <console type='pty'> <target type='virtio'/> </console> Which should create a /dev/hvc0 in the guest The 'virtserialport' device is a paravirt serial port (though it has no baud/parity settings). These are basically reliable, bi-directional data channels between host & guest. These are intended for running guest agents which need to communicate with some host service. These appear as unstable named devices /dev/vportNNNN, and also stable named symlinks /dev/virt-port/UNIQUE-CHANNEL-NAME You can enables these in a libvirt guest by adding devices like <channel type='unix'> <source mode='connect' path='/var/lib/libvirt/myguest-org.myservice'/> <target type='virtio' name='org.myservice'/> </channel> This should create a character device /dev/virtio-port/org.myservice in the guest, which is connected to a UNIX socket '/var/lib/libvirt/myguest-org.myservice' in the host OS. Regards, Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :| -- devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxxx https://admin.fedoraproject.org/mailman/listinfo/devel
